<html lang="en">
 <head>
 <meta charset="UTF-8">
 <title>可视化音频</title>
 <script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
  <style> body {
 display: block;
 background: url("./8.jpg");
 background-position: center;
 background-repeat: no-repeat;
 background-attachment: fixed;
 background-size:100%;
 }
 </style>
 </head>
 <body>
 <input type="file" style="color:red;" name="" value="" id="musicFile"><input type="button" name="startStop" value="暂停" id="startStop">
 <p id="tip" style="color:red;"></p>
 <canvas id="canvas"></canvas>
  <script>
   window.onload = function () {
   canvas.width = window.innerWidth;
   canvas.height = window.innerHeight;
   var canvasCtx = canvas.getContext("2d");
    
   var AudioContext = window.AudioContext || window.webkitAudioContext || window.mozAudioContext;
   var audioContext = new AudioContext();//实例化
    
   $('#musicFile').change(function(){
  //当选择歌曲时，判断当前audioContext的状态，如果在进行中则关闭音频环境，
  //释放audioContext的所有资源，并重新实例化audioContext
  if(audioContext.state == 'running'){
   audioContext.close();
   audioContext = new AudioContext();
  }
    if (this.files.length == 0) return;
    var file = $('#musicFile')[0].files[0];
    var fileReader = new FileReader();
    fileReader.readAsArrayBuffer(file);
    fileReader.onload = function(e) {
    var count = 0;
    $('#tip').text('开始解码')
    var timer = setInterval(function(){
     count++;
     $('#tip').text('解码中,已用时'+count+'秒')
    },1000)
    audioContext.decodeAudioData(e.target.result, function(buffer) {
     clearInterval(timer)
     $('#tip').text('解码成功，用时共计:'+count+'秒')
     var audioBufferSourceNode = audioContext.createBufferSource();
     var analyser = audioContext.createAnalyser();
     analyser.fftSize = 256;
   audioBufferSourceNode.connect(analyser);
   analyser.connect(audioContext.destination);
   audioBufferSourceNode.buffer = buffer;
   audioBufferSourceNode.start();
   var bufferLength = analyser.frequencyBinCount;
   var dataArray = new Uint8Array(bufferLength);
 
   //播放暂停音频
   startStop.onclick = function() {
    if(audioContext.state === 'running') {
     audioContext.suspend().then(function() {
     $("#startStop").val('播放');
    });
    } else if(audioContext.state === 'suspended') {
     audioContext.resume().then(function() {
     $("#startStop").val('暂停');
    }); 
    }
   }
    
   var oW = canvas.width;
   var oH = canvas.height;
   var color1 = canvasCtx.createLinearGradient(oW / 2, oH / 2-10, oW / 2, oH / 2 - 150);
   var color2 = canvasCtx.createLinearGradient(oW / 2, oH / 2+10, oW / 2, oH / 2 + 150);
   color1.addColorStop(0, '#1E90FF');
   color1.addColorStop(.25, '#FF7F50');
   color1.addColorStop(.5, '#8A2BE2');
   color1.addColorStop(.75, '#4169E1');
   color1.addColorStop(1, '#00FFFF');
    
   color2.addColorStop(0, '#1E90FF');
   color2.addColorStop(.25, '#FFD700');
   color2.addColorStop(.5, '#8A2BE2');
   color2.addColorStop(.75, '#4169E1');
   color2.addColorStop(1, '#FF0000');
   function draw() {
    drawVisual = requestAnimationFrame(draw);
    var barHeight;
       // 自定义获取数组里边数据的频步
       canvasCtx.clearRect(0, 0, oW, oH);
       for (var i = 0; i < bufferLength; i++) {
       barHeight = dataArray[i];
       analyser.getByteFrequencyData(dataArray);
       // 绘制向上的线条
    canvasCtx.fillStyle = color1; 
    /* context.fillRect(x,y,width,height)
     * x，y是坐标
     * width，height线条的宽高
     */
    canvasCtx.fillRect(oW / 2 + (i * 8), oH / 2, 2, -barHeight);
        canvasCtx.fillRect(oW / 2 - (i * 8), oH / 2, 2, -barHeight);
        // 绘制向下的线条
        canvasCtx.fillStyle = color2; 
        canvasCtx.fillRect(oW / 2 + (i * 8), oH / 2, 2, barHeight);
        canvasCtx.fillRect(oW / 2 - (i * 8), oH / 2, 2, barHeight);
       }
   };
   draw();
    })
    }
   })
   }
  </script>
 </body>
</html>